The 4 pencil stand works great for the 2G iPhone but if you have a 3G iPhone you may need to use 2 pencils for the horizontal support due to the extra thickness, making a total of 5 pencils for the 3G iPhone (as pictured).
If you have a 3G phone first strap two pencils together with one elastic band at either end to make the horizontal phone support. Then make a triangle using two more pencils. Then add the final pencil as the back support. You can adjust the stability and support given by tightening the top elastic band tension.
Check out more photos and details of Roland's DIY iPhone stand over at Geeky Gadgets.